1. Technical Field
This disclosure is related to an image processing apparatus equipped with an auto-color mode.
2. Related Art
For printing apparatuses such as inkjet recording apparatuses, and image processing apparatuses such as full-color copying machines, auto-color mode has been known in which the apparatus automatically determines whether an original copy is color or monochrome. When this auto-color mode is selected, the apparatus switches the image forming mode (color mode/monochrome mode) based on whether an original copy to be printed or copied is color or monochrome.
As original copy color determination for determining whether an original copy is color or monochrome, there has been known automatic determination through an automatic color selection (ACS) process. In this ACS process, the target of the determination is image data contained in print job data supplied from a computer through a network, and image data inputted by reading an image on an original copy with a scanner or the like. First, pixel color determination is performed to determine whether pixels forming the determination target image data are color pixels or monochrome pixels. Then, by using the results of the determination, it is determined whether the original copy is color or monochrome. Thereafter, color or monochrome printing is performed according to the result of the determination.
Japanese Patent Application Publication No. Hei 5-284372 proposes a color image processing apparatus configured to convert the color of each pixel read by color image reading means into saturation information, then average the saturation information at each of multiple areas on the color image, detect the greatest value of the averaged saturation information for each scan line of the image, and finally perform a histogram analysis. In this color image processing apparatus, the number of colors present in the image is determined from the histogram of the greatest saturation values, and the original copy is determined as monochrome when the number of colors is one, while the original copy is determined as color when the number of colors is more than one.